In the assembly of electronic apparatus it is common practice to employ semiconductor devices which are manufactured in the form of a die and then bonded in position during the manufacture of the electronic apparatus. The semiconductor dies are manufactured by depositing, on a wafer of a material such as silicon dioxide or gallium arsenide, a plurality of different layers of conductive, semiconductive and dielectric materials in precisely defined configurations. When the wafers are completed they are diced into individual dies, which are often very delicate. The individual semiconductor dies are difficult to handle during assembly of electronic apparatus because of their relatively small size and because certain types of semiconductor dies, such as laser diodes, are extremely fragile and thus easily damaged.
Most of the methods which have heretofore been employed to bond the semiconductor dies in position during the manufacture of electronic devices, such as compression die bonding and the like, have proven to be unsatisfactory. Excellent bonding of semiconductor dies can, however, be achieved by a process in which the semiconductor die is joined directly to a mounting surface which has been pre-treated with a material which forms a eutectic bond in situ with the semiconductor die. The die bonding process which is employed includes a combination of heat, pressure and a controlled amount of mechanical agitation, commonly called "scrubbing." The above-noted combination of process steps initiates and promotes satisfactory formation of in situ formed eutectic bonds. Die bonders are commercially available from various sources, such as Kulicke and Soffa Industries, which incorporate features which will provide controlled application of heat and pressure in combination with various selected types of scrubbing action during the die bonding process. The commercially available die bonders are designed for use with a variety of different types of collets to pick up and hold different sizes, shapes and types of semiconductor dies during die bonding. The collets are secured in a chuck or the like of a control arm or similar device of the die bonder. The collets typically include a vacuum conduit which is operationally connected to the die bonder to provide a vacuum for picking up and holding individual semiconductor dies during die bonding.
The commercially available die bonders are generally satisfactory for most applications. It has been found, however, that the collets which are available for use with the die bonder are often unsatisfactory. The most common type of collets has a four-sided configuration with an internal pyramidal-shaped pocket for holding a semiconductor die during die bonding. In the assembly of laser emitters and laser detectors it is critical for proper operation of the final device that the leading edge of the active area of the laser diode be precisely positioned at the edge of the supporting member to which it is to be bonded in order to have proper operation of the device. Using the commonly available four-sided collets it is not possible to observe the leading edge of the laser diode during die bonding for purposes of aligning the leading edge or the laser diode with the edge of the supporting member. Furthermore, the collets heretofore available tend to apply excessive pressure at the edges of the laser diodes, and to the highly fragile active regions of the laser diodes which causes the laser diodes to fracture during die bonding.
What would be highly desirable would be a collet for a die bonder apparatus which would permit more accurate placement of semiconductor dies and would also reduce the amount of damage during die bonding of the semiconductor die to a support member.